A little more than a year ago, Boston Living Center was crumbling and its future in doubt. Its executive director had stolen tens of thousands of dollars from its coffers to feed a gambling habit, leaving the center on the brink of closure and its members with the bitter taste of betrayal.

Now, the region’s largest refuge for people living with HIV and AIDS is on its feet again. Clients are surging. Finances are strong. And recently it hired as executive director Larry Kessler, a longtime crusader for people living with HIV and AIDS.

At 70, Kessler is bent with age and walks with a cane, though his wit is as firm as ever. When asked his age, he quickly retorted: “I’m 39.”

Kessler has stepped away from an easy life of retirement to take charge at the Living Center, and he shows no sign of slowing down.

“I had a nice break,’’ Kessler said, explaining his return to the spotlight. “I was off for five or six years. And I said, ‘I’m missing the action.’ There’s still more work to be done.”

Kessler’s legacy in Boston spans 30 years, starting as a transplant from Pittsburgh who was willing to confront the misinformation, fear, and prejudices of the AIDS epidemic.

The cause had found a warrior. He founded the AIDS Action Committee of Massachusetts, which became a leader in the fight against HIV/AIDS. It pushes for fair and effective AIDS policies, HIV prevention programs, and quality health services for people with the virus. Kessler also founded the AIDS Walk and was among the founding board members of state and city task forces on AIDS.

‘I said “I’m missing the action.’’ There’s still more work to be done.’

“He started as an advocate for people with AIDS when there was nobody else to advocate for them,’’ said Jonathan D. Scott, president of Victory Programs, a nonprofit that merged with the Living Center last year. “Literally he would be the person who would fight for their rights. And I feel like in some ways this is coming full circle [for him] because this organization is so much about direct advocacy.’’

The center began 22 years ago after a group of friends held dinner one Monday evening to give people with HIV and AIDS a place of acceptance and belonging. The group held regular dinners and eventually found space in Back Bay for a center.

At the start, there were devastating days, and death was constant. But as treatment improved and people lived longer, the center’s focus shifted from an emphasis on funerals and grief counseling to improving the quality of life, Kessler and others say.

“Now [that death is] not on the front burner, other things have replaced that — housing needs, jobs, companionship that helps individuals say ‘I may have HIV but I’m still part of a community,’ ’’ Kessler said.

The center offers peer support, workshops, arts classes, and holistic care to its members, many of them poor and many without homes. Meals remain a core part of its mission, and center is still a bedrock of inclusion, a welcoming space.

But in 2010, controversy struck. Board members grew suspicious after they discovered numerous unauthorized cash withdrawals from the center’s savings from 2008 to 2010. They fired executive director Valerie Tebbetts and notified Attorney General Martha Coakley’s office, which investigated.

Tebbetts pleaded guilty to embezzlement in December 2011 and was sentenced to five years probation. A judge ordered her to pay $123,500 in restitution. Tebbetts was also ordered to stay away from casinos, seek counseling for gambling, and not play the lottery. The news was devastating.

“I had known Val,’’ said Justin Jones, a longtime volunteer who sought refuge at the center in 1999 after he was diagnosed with the virus. “I felt violated by somebody I trusted who took from people who did not have a lot.”

With its finances in disarray, the center almost closed and its board of directors sought help from Victory Programs, a 37-year-old organization that serves the homeless population in Boston and Cambridge.

The race to save the center went into overdrive. An emergency fund-raising campaign was launched and within months the center raised more than $210,000 from donors and foundations, according to center figures. Last year, the center and Victory Programs merged.

“I think there was a sinking feeling in the community,’’ said Kessler. “I don’t want to be too grand and overstate it, but in a way it was a version of the sinking of the Titanic. Nobody wanted to see it go down.”

Kessler vows to keep the course steady for the center and return the trust and respect staff and volunteers deserve. He said that in spite of the past problems, the bright light at the center is that it has kept pace with the changing face of AIDS.

He added: “It’s doing pretty well.’’

Meghan Irons can be reached at mirons@globe.com. Follower her on Twitter at MeghanIrons.